Multiphase thermally-actuated circuit controller



G. A. BURNHAM MULTIFHASE THERMALLY ACTUATED CIRCUIT CONTROLLER Dec; 13, 1927. 1,652,346

Filed May 21, 1924 MULTIPHASE THERTMALLY-ACTUA'LED CIRG'UPL @ONTRQLLEE.

Application filed May 21',

This invention relateslto multi-phase circuit protection and has for its object the provision of a single thermally-actuated circuit-controller arranged to be heated by means of the current in the phases of the circuit, to protect the circuit.

Fig. l is a diagram of the invention and the circuiwconnections therefor.

F 2 is a longitudinal sectional elevation through the thermally-actuated device.

Fig. 3 is a perspective View of the protective apparatus embodying the invention.

Fig, 4 is a diagrammatic detail illustrating a modified arrangement for opening the multi-phase switch,

its here shown the inulti-phase circuit with which this invention may be associated may he a three-phase circuit having the three circuit leads 10, ll, and 12 and ada ed for connection with a power-consuming device as the electric motor 13. A three phase electric switch 14.- may be arranged in said circuit leads and may have the handle 15 by which it may he closed and opened "manually, and the trip coil 16 hy which may he opened electrically.

The circuit protective apparatus embody ing the invention includes the transformer having the rectangular core 18 and the two series coils or windings l9 and thereon, which coils are adapted to be connected in series With separate circuit leads and, corn sequently are energized hy currents in diiterent phases of the circuit, As here shown, the coil 19 is in series with the lead it the coil 20 is in series with the lead ll For circuits difierent from the three-phase. circuit shown, there is adapted to he such number of coils, each in a difierent lead and consequently, phase, of the circuit, that the resultant magnetic flux in the core 18 is at tected loy a current change in each phase of the circuit,

A single heating coil 22 is disposed ahoutone of the legs or the core 18 and is adapted to he influenced, through said core, hy the current in: the coils 19 and 20 and to have a current generated therein which is a innetion of the current in said coils. Said heating coil may have but a relatively few turns as compared with the number oi? turns in said coils l9 and 20. Said heatingcoil is adapted to govern the operation of a then wally-actuated circuit-controller 25. Said was. Serial it. treats;

circuit-controller may be constructed as set 55 forth in a co-pending application oi George W, Olteelie, Serial l lo. 557,054, filed April 28,1922, (now Patent no. 1,574,508) and assigned to Sears B. Condit. Said controller may have the tubular insulating casing 26 provided with conducting end-caps 31 and 28 and an insulating plug 29 contained. in one end of the casing under the end L and said plug may have an extension jected through said end cap. it heater nient 31 may extend through the casing 26- hetvveen and be electrically connected with said end caps, A spiral thermostatic element 32, comprising a strip having two united metals of diilerent coetiicients of expansion, may have one end. mechanically fixed to and electrically connected with the end cap 27 and may surround and he maintained spaced from but in the field or heat-influence of the heater element 31: The free end-of said thermostatic element may have a contact 84, which contact may cooperate with a fixed contact to control the circuit including the trip "mil lo lined contact 35 may extend. 1 n the insulating plug 29 and its extension and terminate in an external terminahportion Said circuit controller may he supported reinovahlv in spring clips 3? and 38 which clips are secured to a suitable 39 and are adapted electrically to engage the end caps 2? and 28.

The terminals of the heating coil 22 are connected to the clips or terminal members 3'? and thence, through the end caps :2? and 28, to the heater element 81. Power to actuate the trio coil is me he derived 1 '1 1 Irena any phase or toe three-peace circuit as troro the phase having the c1rcu1t leads 10 l Lead 10 may he connected to the one clip 3'3, for instance, and lead 11 may be connected, through the trip coil, with the contact The contacts and 35 of the circuit controller may he normally open but may close to energize the trip coil. v

As thus arranged, tie flux set up by the current in coils 19 and 20 may he insuflicient to generate enough current in heating coil 22 to heat the heating element 31 suiliciently to move the thermostatic element and close the circuit When, however, an overload occurs in any one, or all, phases of the three ohase circuit, there will he a sulii- I ture 16 is pulled (iii cient amount of current generated in heating coil 9153 to cause the contacts 3% and 35 o' the circuit controller to close, thereby to energize the, trip coil 16 and open the switch 1,1

The single thermal element, therefore, is responsive to abnormal conditions in any one, or all, phases of the multiphase c1rcuit.

I prefer to arrange the various components of the protective device in a unitary structure, as illustrated'in Fig. 3, wherein the supporting base 39 of the circuit-controller is mounted directly on the core 18 of the transformer by the brackets 40. A junc- 5 tion block 41 may be supported on the opopen' its contacts to open the switch 14. In

this figure, the trip coil 16 is adapted to be normally continually energized through the normally-closed contacts of the thermal element; and hold in attracted position an ar mature 16. When the contacts of the thermal element open upon overload, the armaack by the spring 16 and strikes a blow on the locking mechanism of the switch, thereby opening the switch. The idea of circuit-openin contacts in the thermal element is sometimes to be preterrcd over the circuit-closing contacts as less current need be controlled by the contacts.

I claim: I 1. Multi-phase circuit-protective apparatus comprising a switch for the circuit, and

controlling means for the switch including a single thermally-actuated device having a heating element energized by a single source of current derived from the currents in all of the phases of the circuit.

20 Multhphase circuit-protective appa- .ratus comprising a switch for the circuit,

and controlling means for the switch including a thermally-expansible member arranged to be heated and eflept the opening oi the switch, and a single electric heating c0nductor for said expansible member traversed v by a current derived from the currents in all of the phases of the circuit.

3. A multi-phase circuit protective apparatus'including a circuit-controller having a thermally actuated member, and means to actuate said member by the currents in differ ent hases of the circuit including a heating con uctor for said member, and a transform er having a plurality of primary windings which are energlzed by the currents in all oi the phases of the multiphase circuit, and

a single secondary winding common to all of said rimary windings and connected with said eating conductor.

4:. A multi-phase circuit protective apparatus including a circuit-controller having a thermally-actuated member, andmeans to actuate said member by the currents in different phases of the circuit, said means including a heater element disposed in heating relation with said member, and means to heat said element by a current derived from all of the currents in thediflerent phases of the circuit.

' 5. A multiphase circuit protective apparatus including a circuit-controller having a thermally-actuated member, and means to actuate said member by a current derived from all of the currents in the different phases of the circuit, said means includ ng a heater element disposed in heating relatlon with said member, and a transformer c011 responsive to all of the currents in the different phases of the circuit connected with said heater element to supply heating cur rent thereto.

6. A multihase circuit protective apparatus including a circuit-controller having a thermally-actuated member, and means to actuate said member by the currents in dif-.

fcrent phases of the circuit, said means including a heaterelement disposed in heating relation with said member, a transformer coil connected with said heater element to supply heatin current thereto, and coils in different phases of the circuit each arranged independently and all also arranged con ointly to influence the current in said transformer coil.

7. Multi-phase circuit rotective a paratus having a lurality of members a apted to be energized by the currents in the difierent phases of the circuit, and a single thermally-actuated circuit-controller arranged to be inductively influenced by the currents traversing all of said members.

8. Multi-phase circuit protective a paratus having a plurality of coils adapts to be energized by the currents in the different phases of the circuit, a heating coil arranged in the magnetic fields of all of the aforesaid coils to be influenced by the currents traversing all of said coils, and a single thermally-actuated circuit-controller arranged to be influenced by the current in said heating coil.

9. Multi-phase circuit protective apparatus having a plurality of coils adapted to be energized by the currents in the different ranged to be influenced by the current in said heating coil. 1

10. A multi-phase circuit protective device having a magnetizable core, a plurality of windings thereon adapted to be energized by the currents in the different phases of the circuit, a heating coil carried by said core, and a single thermally-actuated circuit-controller arranged to be influenced by the current in said heating coil.

11. A three-phase circuit protective device comprising a rectangular magnetizable core,

.two circuit-windings on the opposite legs of the core, each winding adapted to be connected in a separate phase of the circuit, a heating coil on another leg of the core, a support for said core, a base carried by said sup ort and having terminal members for sai heating coil, and a thermally-actuated .heatin 'base disposed above and supported by said circuit-controller removably received in andv supported by and connected electrically with said terminal members.

12. A three-phase circuit protective device comprising a rectangular magnetizable core, two circuit-windings on the opposite legs of the core, each winding ada ted to be connected in a separate phase 0 the circuit, a coil on another leg of the core, a

core, terminal members for said heating coil carried by said base, and a thermally-actuated circuit-controller received in and electrically connected with said terminal members.

In testimony whereof, Iihave signed my name to this specification.

GEORGE A. BURNHAM. 

